The present invention relates to readily absorbable enteral pharmaceutical formulations of cardiac glycosides, which are poorly absorbable per se, and to a method for preparing such formulations.
Because of their favorable effect on the force of the myocardial contraction, cardiac glycosides are used therapeutically as cardiotonics for the treatment of myocardial insufficiency and congestive heart failure. Yet such a treatment has the disadvantage that upon enteral application, most of the cardiac glycosides are absorbed only to a low and unpredictable percent and thus, a safe therapy can often be achieved only by intravenous injection. Therefore, various attempts have been made to bring cardiac glycosides into a form which is suitable for enteral application.
Chemical derivations of such glycosides have been successful to a certain degree in some cases, e.g., digitoxin or digoxin, which are absorbable completely or to at least an acceptable degree, respectively. Yet other cardiac glycosides, such as, e.g., g- and k-strophanthin and proscillaridin still have to be administered parenterally, that is, intravenously, because of their insufficient enteral absorbability.
For several pharmacologically active agents, it has been proposed to dissolve or suspend them in glycerides of fatty acids having a medium chain length in order to improve their absorption. Thus, for example, according to German Pat. No. 1,282,853, chloramphenicol is suspended in triglycerides of fatty acids having a medium chain length. Belgian Pat. No. 567,598 discloses a suspension of antibiotics in triglycerides. British Pat. No. 1,432,784 discloses a solution or suspension of various pharmacologically-active agents in monoglycerides and German Offenlegungsschrift No. 2,357,389 discloses the solution or suspension of the same agents in a mixture of triglycerides and partial glycerides. Yet insofar as any data relative to the achieved absorption are included in the above references, these data indicate only little improvement of the absorption of the respective pharmacologically-active ingredients.